In order to obtain high quality decorative color, we usually use AIP(arc ion plating) in PVD technology. It produces durable colors. The main coatings is TiN(titanium nitride) and it's golden. The work temperature for AIP coating is more than 150 centigrade, so it is suitable for glass, ceramic, metals.
PVD requires very good surfaces for the substrates. The surface must be dry, clean, and smooth. It also requires hardness. Aluminum or Zinc is not suitable to be PVD coated. In this case, we can make the aluminum and Zinc pieces with electroplating layer.